Carb Tuning

[rm17742]

Hello all... I am a long time lurker, first time poster and I plan on posting more! Yall have cost me a lot of money over the last few years, but I have some great saws to show for it.

Here is my deal: I just picked up a new Makita 401 on ebay as a backup to my 346xp. I decided to do my 1st muffler mod which turned out really well. I have a Baileys tach and set the saw to 12,000 RPM as recommended by the manufacturer. The problem is that the saw still sounds really rich to me. It constantly 4 strokes at WOT.

My Question is - do you tune by RPM alone since I have a tach, or should I exceed the recommended RPM and lean it out until it just begins to 4 stroke? Am I doing something wrong by having it run rich which still running at 12,000 RPM? I just adjusted my high screw until I hit that mark and quit. I am just concerned because I would probably run it leaner if I didn't have a tach and know what the speed is (it would "feel better").

Thanks!

===Russell

346XP
359
334T
DCS-6401 (with a bow bar!)
DCS-401
029 (my first saw @ 15)

 

[ray benson]

The owners manual says low and high mixture screws 1 turn open from seated position. I would run the saw and adjust the low screw to eliminate hesitation when accelerating. Then adjust the high screw for best performance under load. Then I check the speed with the tach and make a note for future reference.
http://www.makita.com/assets_product/DCS401/owners_manuals/995707805_(GB,F).pdf

 

[blsnelling]

Give the engine what it wants. If it's running rich at 12K, lean it out a little at a time.

 

[rm17742]

Thanks for the advice... I may lean it out a little bit, but I don't want to get carried away. Thanks!

 

[ShoerFast]

Thanks for the advice... I may lean it out a little bit, but I don't want to get carried away. Thanks!

By far the best tuning aid is a stopwatch and a good straight clean log.

From right were your saw is, or fatter, cut a timed cookie, lean it maybe 5 minutes worth.

Cut again repeat.

What you will see is a cut @ (for a say)

@ 1 1/4 fat a 10 second cut

@ 1 1/8 fat a 12 second cut

@ 1 turn out a 9 second cut (Most saws fall real flat on there face when you hit that 'too lean' stage.)

back out a little...

@ 1 1/16 out a 13 second cut, bingo, your there.

Most saws 'perfect' have a little burble out of the wood, but go to town in the wood.

 

[daemon2525]

Well, shoer done lost me!!!

 

[rm17742]

Thanks for the good advice . I'll post results later.

 

[2FatGuys]

ShoerFast ---

Let me get this right... you are tuning for a SLOWER cut? Why?

 

[Mad Professor]

Well, shoer done lost me!!!

I think he mixed up the 9 with the 13 and should have started with 12

 

[Junkyard Jim]

I think he mixed up the 9 with the 13 and should have started with 12

I sure hope so or I've had a nap and need to be retrained

 

[RiverRat2]

I think he mixed up the 9 with the 13 and should have started with 12

Yeah!!!!!! He's FUBAR!!!!!! I thought 10 was good @ 1+ 1/4?????????